AutoCAD

Bug Watch: Part of the CUIrate's Egg Isn't Rotten After All

15 Nov, 2005 By: Steve Johnson Cadalyst

Selection Preview is not all there in AutoCAD 2006, but tablet support is.


A potentially handy new AutoCAD 2006 feature is Selection Preview. The idea is that AutoCAD allows you to see what you are selecting before you actually select it. So far, it only works while picking individual objects. Hopefully, a future release will expand this feature to the other selection methods, if performance permits. The colored rectangles AutoCAD 2006 displays while using Window and Crossing are not particularly useful. The not-quite-finished feel to this feature includes the following pair of insects.

Snap Out of It (2006 to 2006 SP1)
If you work with your Snap turned on, Selection Preview doesn't work properly. To see this, set Snap to 1 and on. Draw a line from 0,0 to 5,1 and select Zoom Extents. At the Command prompt, place your cursor at 1,0, move your mouse slowly up and observe. The cursor stays where it is, as it should with Snap on. However, when you move your mouse, you are invisibly moving between snap points. If you move far enough, the cursor snaps to the next point, as it always has done. The problem occurs before you get to that point. As you move very slowly upwards from 1,0, as your invisible cursor passes over the line, the line is highlighted. While it is highlighted, select it. You will miss it because AutoCAD is correctly using the snapped point (1,0) rather than the invisible cursor point.

The bug is that AutoCAD is using the invisible cursor to determine which objects to highlight, rather than the visible cursor. This results in false positives, as above, and also false negatives. If you move the cursor to 0,0, the line is highlighted. Move up a bit, and the highlighting is turn off. If you pick, the line is selected, even though Selection Preview implies that it will not.

Workaround: None known.

Group Therapy (2006 to 2006 SP1)
Another Selection Preview oddity is the way it works with groups. In AutoCAD's default state, if you hover over an object that belongs to a group, the whole group is highlighted. That implies that picking the object will result in the selection of the whole group, but that's not necessarily the case. If group selection is turned off, you will select only the object under your cursor. You can choose to turn off Selection Preview for groups altogether, but there's no setting to have it correctly highlight groups only when appropriate.

Workaround: None known.

UCS Not In Control (2000 to 2006 SP1)
The UCS II toolbar contains a useful pull-down tool for displaying the current UCS and switching to any other named UCS. You can include the UCSManager control in your custom menus. The problem is that it doesn't always display the current UCS because it ignores the Undo command. If you undo back beyond a point where you switched to another UCS, AutoCAD correctly undoes the UCS operation, but the UCSManager control takes no notice. It carries on displaying whatever it was displaying before, meaning that you may end up drawing things in a different plane than the one you thought you were.

Workaround: While you can't stop the control from getting out of sync, you can bring it back into sync simply by clicking on it twice.

A CUIrate's Egg Revisited
In August's Bug Watch I stated that AutoCAD 2006 doesn't like working with tablets. Several people had reported this, and as I no longer have a tablet to check this, I took their word for it. However, it seems that both they and I were wrong. Several people have since pointed out that their tablets and pucks are fully functional under AutoCAD 2006, so I owe an apology to both you and Autodesk.

I fell into the trap of mistaking driver issues for an AutoCAD bug. This is a case where following the standard support person's advice of "update to the latest drivers" can be a bad idea. The latest Calcomp TabletWorks driver, v10, does not have button mapping that works with AutoCAD. This was removed for legal reasons, making the driver less than useful. People using TabletWorks driver v7.46 report that they still have a functioning tablet in all AutoCAD releases.


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Lynn Allen

Autodesk Technical Evangelist Lynn Allen guides you through a different AutoCAD feature in every edition of her popular "Circles and Lines" tutorial series. For even more AutoCAD how-to, check out Lynn's quick tips in the Cadalyst Video Gallery. Subscribe to Cadalyst's free Tips & Tools Weekly e-newsletter and we'll notify you every time a new video tip is published. All exclusively from Cadalyst!
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